| Shixingoolithus Temporal range: | |
|---|---|
Egg fossil classification  | |
| Basic shell type: | † Dinosauroid-spherulitic |
| Oofamily: | † Stalicoolithidae |
| Oogenus: | † Shixingoolithus Zhao et al., 1991 |
| Oospecies | |
| |
Shixingoolithus is an oogenus of dinosaur egg from the Cretaceous of Nanxiong, China. [2] [3]
Shixingoolithus eggs are nearly spherical, and about 12 cm in diameter, with a shell thickness of 2.3–2.6 mm. The shell is made up of tall, prismatic units, and has narrow, irregular pore canals. Its cone layer (mammillae) is approximately a fourth of the shell thickness. [3] [4]
Shixingoolithus probably represents eggs of an ornithopod dinosaur. [5] [6] They are known from the Pingling Formation and Chishan Formation (from the Upper Maastrichtian), but are absent from the Yuanpu Formation, indicating that they disappeared in the last 200,000 to 300,000 years of the Cretaceous. [7] [8]
Shixingoolithus was initially described as a member of the Spheroolithidae on the basis of its spherical shape, and similarities to other spheroolithid eggs. [7] [3] In 2012, Wang et al. classified Shixingoolithus in a new oofamily, Stalicoolithidae, alongside Stalicoolithus and Coralloidoolithus , because of the secondary eggshell units found in its pore canals. [9] However, these secondary shell units may in fact simply be taphonomic artifacts. It has also been speculated to in fact be a dendroolithid, but a more complete description must be made before its classification can be resolved. [6]
Elongatoolithus is an oogenus of dinosaur eggs found in the Late Cretaceous formations of China and Mongolia. Like other elongatoolithids, they were laid by small theropods, and were cared for and incubated by their parents until hatching. They are often found in nests arranged in multiple layers of concentric rings. As its name suggests, Elongatoolithus was a highly elongated form of egg. It is historically significant for being among the first fossil eggs given a parataxonomic name.
Dendroolithus is an oogenus of Dendroolithid dinosaur egg found in the late Cenomanian Chichengshan Formation, in the Gong-An-Zhai and Santonian Majiacun Formations of China and the Maastrichtian Nemegt and Campanian Barun Goyot Formation of Mongolia. They can be up to 162 mm long and 130 mm wide. These eggs may have been laid by a Therizinosaur, Sauropod, or Ornithopod. The oospecies "D." shangtangensis was originally classified as Dendroolithus, however, it has since been moved to its own distinct oogenus, Similifaveoloolithus. This oogenus is related with embryos of the theropod Torvosaurus
Dictyoolithus is an oogenus of dinosaur egg from the Cretaceous of China. It is notable for having over five superimposed layers of eggshell units. Possibly, it was laid by megalosauroid dinosaurs.
Faveoolithus is an oogenus of dinosaur egg. The oogenus contains two oospecies, F. ningxiaensis and F. zhangi.
Ovaloolithus is an oogenus of dinosaur egg. Eggs of the genus have been found in China, Mongolia and Utah.
Macroelongatoolithus is an oogenus of large theropod dinosaur eggs, representing the eggs of giant caenagnathid oviraptorosaurs. They are known from Asia and from North America. Historically, several oospecies have been assigned to Macroelongatoolithus, however they are all now considered to be a single oospecies: M. carlylensis.
Macroolithus is an oogenus of dinosaur egg belonging to the oofamily Elongatoolithidae. The type oospecies, M. rugustus, was originally described under the now-defunct oogenus name Oolithes. Three other oospecies are known: M. yaotunensis, M. mutabilis, and M. lashuyuanensis. They are relatively large, elongated eggs with a two-layered eggshell. Their nests consist of large, concentric rings of paired eggs. There is evidence of blue-green pigmentation in its shell, which may have helped camouflage the nests.
Phaceloolithus is an oogenus of dinosaur egg found in the Fenshui'ao Formation of the Dongting Basin of the Hunan Province of China. The eggs have a subspherical shape, measuring up to 168 mm on the long axis, and having a very thin shell.
Porituberoolithus is an oogenus of dinosaur egg found in the late Campanian Oldman Formation and Dinosaur Park Formation of Alberta, the Fossil Forest Member of the Fruitland Formation in New Mexico, the Upper Shale Member of the Aguja Formation in Texas and Cerro del Pueblo Formation of Mexico. It was originally described as distinct from the Elongatoolithids on the basis of its ornamentation, but it was listed as a member of that oofamily by Wang et al. 2010. It is very similar to Subtiliolithus, but has a thicker shell.
Egg fossils are the fossilized remains of eggs laid by ancient animals. As evidence of the physiological processes of an animal, egg fossils are considered a type of trace fossil. Under rare circumstances a fossil egg may preserve the remains of the once-developing embryo inside, in which case it also contains body fossils. A wide variety of different animal groups laid eggs that are now preserved in the fossil record beginning in the Paleozoic. Examples include invertebrates like ammonoids as well as vertebrates like fishes, possible amphibians, and reptiles. The latter group includes the many dinosaur eggs that have been recovered from Mesozoic strata. Since the organism responsible for laying any given egg fossil is frequently unknown, scientists classify eggs using a parallel system of taxonomy separate from but modeled after the Linnaean system. This "parataxonomy" is called veterovata.
Paraelongatoolithus is a late Cretaceous oogenus of Chinese fossil egg, classified in the oofamily Elongatoolithidae, which represents the eggs of oviraptorosaurs.
Coralloidoolithus is an oogenus of dinosaur egg from the Tiantai Basin in Zhejiang Province, containing a single known oospecies C. shizuiwanensis. Formerly, it was classified in the oogenus Paraspheroolithus; however, it was considered sufficiently different to be classified in its own genus. C. shizuiwanensis is similar to Stalicoolithus, leading to their classification in the same family, Stalicoolithidae.
Similifaveoloolithus is an oogenus of fossil dinosaur egg from the Tiantai basin in Zhejiang Province, China. It is the sole known oospecies of the oofamily Similifaveoloolithidae.
Hemifaveoloolithus is an oogenus of fossil dinosaur egg from the Tiantai basin in Zhejiang Province, China. It is a faveoloolithid, having spherical eggs roughly 13 cm in diameter. The shell is distinctive for being composed of four or five superimposed layers of shell units, and the honeycomb-like arrangement of pore canals.
Parafaveoloolithus is an oogenus of Faveoloolithid fossil egg, known from the Cretaceous of China.
Elongatoolithidae is an oofamily of fossil eggs, representing the eggs of oviraptorosaurs. They are known for their highly elongated shape. Elongatoolithids have been found in Europe, Asia, and both North and South America.
Polyclonoolithus is an oogenus of fossil dinosaur egg. It is from the Early Cretaceous of Gansu, China. They have distinctive, branching eggshell units, which may represent the original form of spheroolithids.
Dictyoolithidae is an oofamily of dinosaur eggs which have a distinctive reticulate organization of their eggshell units. They are so far known only from Cretaceous formations in China.
Nanhsiungoolithus is an oogenus of dinosaur egg from the late Cretaceous of China. It belongs to the oofamily Elongatoolithidae, which means that it was probably laid by an oviraptorosaur, though so far no skeletal remains have been discovered in association with Nanhsiungoolithus. The oogenus contains only a single described oospecies, N. chuetienensis. It is fairly rare, only being know from two partially preserved nests and a few eggshell fragments.
Spheroolithidae is an oofamily of dinosaur eggs. It contains Guegoolithus, Spheroolithus, and Paraspheroolithus. Like modern birds, the eggshell membrane formed before the calcareous part of the shell.
